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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Small hyaluronan oligosaccharides induce inflammation by engaging both toll-like-4 and cd44 receptors in human chondrocytesGiuseppe M. Campo, Angela Avenoso, Salvatore Campo, Angela D'Ascola, Giancarlo Nastasi, Alberto CalatroniTo cite this version: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Page 1 Adding HA fragments to chondrocyte cultures up-regulated CD44 and TLR-4 expression, activated NF-kB translocation and increased the pro-inflammatory cytokines TNF-α, IL-6 and IL-1β.The addition of a specific CD44 blocking antibody reduced CD44 and all inflammatory cytokine expression as well as protein production. However, cytokine expression remained significantly higher than in untreated chondrocytes. TLR-4 expression was not affected. The treatment with TLR-4 blocking antibody decreased TLR-4 and inflammatory cytokine expression, although cytokine expression was significantly higher than in control cells. CD44 expression was unaffected.The addition of both CD44 and TLR-4 blocking antibodies significantly reduced CD44, TLR-4 and inflammatory cytokine expression.

Previous studies have reported that low molecular mass HA and highly polymerized HA respectively elicited pro- and anti-inflammatory responses by modulating the toll-like receptor 4 (TLR-4) and the TLR-2. The activation of TLR-4 and TLR-2 mediated by collagen-induced arthritis (CIA) induces the myeloid differentiation primary response protein (MyD88) and the tumor necrosis factor receptor-associated factor 6 (TRAF6), and ends with the liberation of NF-kB which, in turn, stimulates pro-inflammatory cytokine production. The aim of this study was to investigate the influence of high molecular weight HA at different concentrations on TLR-4 and TLR-2 modulation in CIA in mice. Arthritis was induced in mice via intradermal injection of an emulsion containing bovine type II collagen in complete Freund's adjuvant. Mice were treated with HA intraperitoneally daily for 30days. CIA increased TLR-4, TLR-2, MyD88 and TRAF6 mRNA expression and the related protein in the cartilage of arthritic joints. High levels of both mRNA and related protein were also detected for tumor necrosis factor alpha (TNF-α), interleukin 1-beta (IL-1-β), interleukin-17 (IL-17), matrix metalloprotease-13 (MMP-13) and inducible nitric oxide synthase (iNOS) in the joint of arthritic mice. HA treatment significantly limited CIA incidence and decreased all the parameters up-regulated by CIA. The improvement of biochemical parameters was also supported by histological analysis, plasma and synovial fluid HA levels. These results suggest that the TLR-4 and TLR-2 play an important role in the arthritis mechanism and the interaction/block of HA at high molecular mass may reduce inflammation and cartilage injury.

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Previous studies reported that hyaluronic acid (HA), chondroitin sulphate (CS) and heparan sulphate (HS) were able to reduce the inflammatory process in a variety of cell types after lipopolysaccharide (LPS) stimulation. The aim of this study was to investigate the anti-inflammatory effect of glycosaminoglycans (GAGs) in mouse articular chondrocytes stimulated with LPS. Chondrocyte treatment with LPS (50 microg/ml) generated high levels of TNF-alpha, IL-1beta, IL-6, IFN-gamma, MMP-1, MMP-13, iNOS gene expression and their related proteins, increased NO concentrations (evaluated in terms of nitrites formation), NF-kappaB activation and IkBalpha degradation as well as apoptosis evaluated by the increase in caspase-3 expression and the amount of its related protein. The treatment of chondrocytes using two different doses (0.5 and 1.0 mg/ml) of HA, chondroitin-4-sulphate (C4S), chondroitin-6-sulphate (C6S), HS, keratan sulphate (KS) and dermatan sulphate (DS) produced a number of effects. HA exerted a very small anti-inflammatory and anti-apoptotic effect while it significantly reduced NO levels, although the effect on iNOS expression and activity was extremely slight. C4S and C6S reduced inflammation mediators and the apoptotic process. C6S failed to decrease NO production, although iNOS expression and activity were significantly reduced. HS, like C4S, was able to reduce all the effects stimulated by LPS treatment. KS and DS produced no reduction in any of the parameters considered. These results give further support to the hypothesis that GAGs actively participate in the regulation of inflammatory and apoptotic processes.